Medical device guide wires are used for a variety of purposes in the treatment of many minimally invasive procedures. Medical device guide wires are manufactured in a range of diameters including 0.014 inch, 0.018 inch, 0.025 inch, 0.032 inch, 0.035 inch and 0.038 inch and a range of lengths including 150 centimeters, 180 centimeters and 300 centimeters. Medical device guide wires are often used in a procedure to provide a pathway over which a therapeutic device such as a catheter is passed. Medical device guide wires are used in many areas of treatment including interventional cardiology, interventional radiology, interventional bronchospy, gastroenterology and urology for a variety of purposes including the placement of vena cava filters, cryotherapy, biliary drainage, angioplasty and stenting.
Catheters are inserted to various locations within a patient for a wide variety of purposes and medical procedures. For example only, one type of catheter is used in percutaneous catheter intervention (PCI) for the treatment of a vascular constriction termed a stenosis. In this instance, the catheter has a distally mounted balloon that can be placed, in a deflated condition, within the stenosis, and then inflated to dilate the narrowed lumen of the blood vessel. Such balloon dilation therapy is generally named percutaneous transluminal angioplasty (PTA). The designation PTCA, for percutaneous transluminal coronary angioplasty, is used when the treatment is more specifically employed in the vessels of the heart. PTCA is used to dilate restrictions in the coronary arteries that have become narrowed or occluded by a build-up of cholesterol fats or atherosclerotic plaque. The balloon at the distal end of the catheter is positioned within the stenosis and inflated causing the stenosis to widen.
The dilation of the occlusion, however, can form flaps, fissures and dissections, which may result in reclosure of the dilated vessel or even perforations in the vessel wall. Implantation of a stent can provide support for such flaps and dissections and thereby prevent reclosure of the vessel or provide a patch repair for a perforated vessel wall until corrective surgery can be performed. A stent is typically a cylindrically shaped device formed from wire(s) or a metal tube with segments of the tube removed. A stent is deployed in a body lumen from a radially compressed configuration into a radially expanded configuration that allows it to contact and support a body lumen. A stent may be implanted during an angioplasty procedure by using a balloon catheter with a radially compressed stent mounted onto the balloon of the catheter. The stent radially expands as the balloon is inflated, forcing the stent into contact with the body lumen, thereby forming a supporting relationship with the lumen walls. Alternatively, self-expanding stents may be deployed with a sheath-based delivery catheter. Deployment is effected after the stent has been introduced percutaneously, transported transluminally and positioned at a desired location by the delivery catheter. Typically, retraction of the sheath covering the radially compressed stent allows the self-expanding stent to deploy. In addition to angioplasty and stenting procedures, other therapeutic procedures often require use of a delivery catheter, such as drug delivery, embolic filters, occlusion devices, diagnostic devices and radiation treatment.
Typically, the placement of such therapeutic delivery catheters involves the use of a guide wire, which may be inserted into the patient's vasculature through the skin, and advanced to the location of the treatment site. The delivery catheter, which has a lumen adapted to receive the guide wire, then is advanced over the guide wire. Alternatively the guide wire and delivery catheter may be advanced together, with the guide wire protruding from the distal end of the delivery catheter. In either case, the guide wire serves to guide the delivery catheter to the location to be treated.
In cases where the lesion targeted for treatment is located distant from a convenient vascular access location, the therapeutic procedure usually starts with the introduction of a guiding catheter into the vascular system from an easily reachable site, such as through the femoral artery in the groin area or other locations in the arm or neck. The guiding catheter is advanced through the arterial system until its distal end is located near the stenosis that is targeted for treatment. During PTCA, for example, the distal end of the guiding catheter is typically inserted only into the ostium or origin of a coronary artery. A guide wire may then be advanced through a main lumen in the guiding catheter and manipulated into position across the stenosis.
Coronary guide wires are flexible and susceptible to buckling and kinking. The distal end of a coronary guide wire, for example, is typically more flexible than the proximal end of the coronary guide wire. During PTCA the distal end of the guide wire must be tracked through the aortic arch and into a coronary artery or a coronary artery side branch vessel. The proximal end of the guide wire is generally stiffer than the distal end of the guide wire to provide sufficient column support to enable advancing of the guide wire through the vasculature. The proximal end of the guide wire must however be flexible enough to enable the guide wire to track through any tortuosity that exists. In instances where the guide wire is advanced independent of the catheter device dexterity is required while advancing the guide wire through the main lumen of the guide catheter to ensure no buckling or kinking of the guide wire occurs. Typically the guide wire is advanced in incremental pushes whereby a physician advances the guide wire by holding the wire a short distance proximal from the proximal end of the guide catheter lumen and advances this segment of guide wire up to the proximal end of the guide catheter lumen. This process is repeated until the guide wire is positioned across the stenosis. In effect the guide wire is advanced through the vasculature with a series of incremental pushes. A torque handle device may be loaded onto the proximal end of the guide wire. The torque handle enables a physician to torque the guide wire to enable steering of the distal end of the guide wire for the purpose of steering the guide wire into a side branch vessel or to assist in crossing through a stenosis. Once the guide wire is in position the torque handle may be loosened and carefully removed while ensuring no longitudinal movement of the guide wire occurs. When the guide wire is in position the proximal end of the guide wire is typically rested on a surface extending from its entry point into the vasculature. During PTCA for example, when the access location is the femoral artery, the proximal end of the guide wire is often rested on a sheet that covers the patient's legs. This is not a very even surface so care must be taken to ensure that the proximal end of the guide wire remains stationary prior to advancing any therapeutic catheters over the guide wire or that the proximal end of the guide wire does not become kinked or damaged due to inadvertent manipulation.
A therapeutic delivery catheter such as a balloon catheter or a stent delivery system may then be advanced over the pre-positioned guide wire until the therapeutic element of the catheter is properly positioned at the treatment site. Three general types of catheters used during PTCA for example are: “over-the-wire” (OTW) catheters, “rapid exchange” (RX) catheters and “fixed wire” (FW) or “a balloon on a wire” catheters. An over-the-wire (OTW) catheter comprises a guide wire lumen that extends the entire length of the catheter. An OTW catheter typically has a “co-axial” catheter construction, wherein two hollow tubes are nested together. The inner tube can slidably receive guide wires and the annular luminal space formed between the inner and outer tubes is used for inflation/deflation fluid. OTW catheters have many advantages traceable to the presence of a full-length guide wire lumen such as good stiffness and pushability for readily advancing the catheter through tortuous vasculature and across tight stenoses. The full-length guide wire lumen is also available for transporting radiocontrast dye to the stenosed artery, for making pressure measurements, for infusing drugs and for other therapies. The full length guide wire lumen permits removal and replacement of a guide wire in an in-dwelling catheter, as may be required to alter the shape of the guide wire tip or if the guide wire becomes damaged.
In instances where a guide wire is first advanced into the vasculature and positioned across a stenosis followed by an OTW catheter, the distal end of the OTW catheter is loaded onto the proximal end of the pre-positioned guide wire and carefully advanced while the guide wire is held stationary distal to the distal end of the OTW catheter. When the proximal end of the guide wire exits from the proximal end of the OTW catheter the guide wire may be held at the proximal end to ensure that no movement of the guide wire occurs as the OTW catheter is advanced. For example, FIG. 1A depicts an illustration of a treatment procedure where OTW catheter 107 has been loaded onto the pre-positioned guide wire 103. FIG. 1B is an enlarged sectional view of the aortic arch and the coronary arteries and the distal ends of the guide wire and the guide catheter. Patient 100 is positioned on his/her back on operating table 101. Sheet 102 is positioned covering the legs and abdomen of patient 100. Guide catheter 105 has been inserted through femoral artery access location 109 and advanced through aorta 104 to aortic arch 110 and guide catheter tip 111 is positioned in ostium 113 of coronary vessel 112. The proximal end of guide catheter 105 rests on sheet 102. Tuohy buorst device 106 is connected to the proximal end of guide catheter 105. Guide wire 103 has been advanced through tuohy buorst adapter 106 and advanced through the lumen of guide catheter 105. Guide wire distal end 115 is positioned across stenosis 114. OTW catheter 107 has been loaded onto guide wire 103. Guide wire proximal end 108 has exited from the proximal end of OTW catheter 107.
In the illustration shown in FIG. 1A the proximal portion of guide wire 103 protruding from the patient must be longer than the length of OTW catheter 107 to enable guide wire 103 to be held when it exits from the proximal port of the guide wire lumen of OTW catheter 107 prior to the distal end of OTW catheter 107 entering into the vasculature. This is to facilitate changing the holding point of guide wire 103 from a point distal to OTW catheter 107 to a point proximal to OTW catheter 107 when guide wire 103 exits from the proximal end of the guide wire lumen of OTW catheter 107. As a consequence, the length of a guide wire required to advance an OTW catheter over a pre-positioned guide wire must be greater than the length of the OTW catheter plus the length of the segment of the guide wire pre-positioned within the vasculature. For example, an OTW PTCA catheter may typically be on the order of 145 centimeters long so that a guide wire used in conjunction with such a catheter may be on the order of 300 centimeters long. This is disadvantageous insofar as this length of guide wire protruding from the patient may be difficult to manage and may be susceptible to inadvertent movement or kinking. For example, when the access point is the femoral artery the proximal end of the guide wire is typically rested on the sheet covering the patient's legs. This is an uneven surface compared to a table top or the like so that care must be taken to ensure that the segment of guide wire protruding from the patient does not move upon this uneven surface or does not become kinked due to inadvertent manipulation of the unsupported guide wire segment.
Catheter designs have been developed that partially address the aforementioned shortcomings of OTW catheters. Rapid exchange (RX) catheters have a guide wire lumen that extends within only the distal portion of the catheter. Catheters of this type are formed so that the guide wire is located outside of the catheter except for the distal portion of the catheter that encompasses the guide wire lumen. The rapid exchange catheter's proximal exit port for the guide wire is typically located about 5 centimeters to 30 centimeters proximal to the catheter distal end. With an RX catheter the guide wire is typically inserted and positioned within the vasculature. The distal tip of the RX catheter is then loaded onto the proximal end of the pre-positioned guide wire while holding the guide wire at a location distal to the distal tip of the RX catheter to ensure that no movement of the pre-positioned guide wire occurs. Alternatively the tuohy buorst adapter may be tightened upon the pre-positioned guide wire to ensure no longitudinal movement occurs. The guide wire can be held at the proximal end when it exits from the proximal guide wire port of the RX catheter. Typically a guide wire of the order of 180 centimeters long is sufficient when used with a RX catheter as the segment of the pre-positioned 180 centimeter guide wire protruding from the patient is longer than the guide wire lumen of the RX catheter and enables the guide wire to be held proximal to the proximal guide wire port of the RX catheter before the distal tip of the RX catheter enters the vasculature.
A significantly shorter segment of guide wire protrudes from the patient when using a RX catheter and a guide wire of the order of 180 centimeters in length as opposed to an OTW catheter and a guide wire of the order of 300 centimeters in length. This shorter segment of guide wire protruding from the patient is more manageable than the segment of the longer guide wire protruding from the patient when used in conjunction with an OTW catheter. Nevertheless, the proximal segment of guide wire protruding from the patient must be rested on a typically uneven surface and care must be taken to ensure no inadvertent movement of the guide wire occurs or that the unsupported segment of guide wire protruding from the patient does not become kinked due to inadvertent manipulation.
Although an RX catheter system may avoid the requirement of using guide wires of the order of 300 centimeters in length, there are some noted difficulties with this type of catheter. Without a full length guide wire lumen, the proximal shaft of a RX catheter lacks an OTW catheter's coaxial relationship with the guide wire, which provides optimal transmission of force to push the distal end of the catheter through tight stenoses or/and tortuous blood vessels. When a RX catheter is advanced through a guide catheter over a guide wire only the distal portion of the RX catheter encapsulates the guide wire. The remaining proximal portion of the catheter runs alongside the guide wire within the guide catheter. This portion of the catheter lacks the coaxial relationship with the guide wire that exists along the full length of an OTW catheter being advanced under similar circumstances. As a result the proximal portion of a RX catheter is more susceptible to buckling within the guide catheter. Improvements to RX catheters have incorporated stiff metal proximal shafts and axial overlap between the stiff proximal shaft and the guide wire lumen to overcome the deficiencies discussed above. Nevertheless, such RX catheters still are not optimal in terms of transmission of force to push the distal end of the catheter.
Another difficulty associated with RX catheters is that it is not possible to exchange guide wires in an in-dwelling RX catheter as can be done with an OTW catheter. Since the proximal guide wire port of an in-dwelling RX catheter is contained within the lumen of a guide catheter it is not possible to retract the guide wire from the guide wire lumen of the RX catheter and subsequently re-advance the guide wire into the proximal guide wire port of a RX catheter as may be required to reshape the tip of the guide wire or to replace the existing guide wire due to, for example, damage to the tip of the guide wire.
Another difficulty associated with RX catheters is encountered at the proximal end of the catheter system. There the RX catheter and the guide wire extend from the guiding catheter side by side, making it awkward to seal the system against blood loss during manipulation of the guide wire and/or the RX catheter. A “Tuohy Buorst” fitting is typically used to form a seal at the proximal end of the guiding catheter to prevent blood loss from the system during manipulation of the guide wire and/or the RX catheter within the vasculature. The “Tuohy Buorst” fitting typically contains a manually adjustable, elastomeric, cylindrical gasket with a round center hole. Adjustment of the elastomeric gasket in the form of longitudinal compression causes the center hole to reduce in diameter and hence form a seal around the indwelling device(s) to prevent blood loss from the patient. This arrangement works well for an OTW catheter because only a cylindrical shaft extends from the guiding catheter since the guide wire is encapsulated within the cylindrical shaft arrangement. However, with a RX device, since the guide wire runs alongside the proximal shaft of the RX catheter, it is more difficult for the “Tuohy Buorst” device to seal against blood loss.
A RX catheter does not contain a full length guide wire lumen, so a physician cannot use the guide wire lumen for other purposes such as injection of contrast dye distal to the stenosis, infusing of therapeutic drugs, or for pressure measurements.
Another type of catheter device known as a “fixed wire” (FW) or “a balloon on a wire” catheter typically incorporates a non-removable guide wire into the design of the catheter. FW catheters typically have a short segment of guide wire protruding from the distal end of the catheter. In use a FW catheter may be advanced through a guide catheter without the requirement of having to advance a separate guide wire because the guide wire is an integral part of the FW device. The distal segment of guide wire is typically of the order of 1-2 centimeters in length and protrudes distally from the distal end of the balloon of such catheters. In addition there is not any segment of guide wire protruding proximally from the device that may be subjected to inadvertent movement or kinking. When a FW catheter is advanced through the vasculature the distal segment of guide wire assists in guiding the catheter through the vasculature. The tip segment may also be shaped into a bend configuration to assist in crossing through a stenosis or selecting a side branch vessel. Torqueing the proximal end of such a FW catheter will result in the distal segment rotating to assist steering of the device through the vasculature to enable crossing through a stenosis or selection of a side branch vessel. However, by the nature of the design of a FW catheter, the distal end of the catheter is typically already within the vessel when the guide wire tip section is being negotiated across a stenosis or being negotiated into a side branch vessel. In such instances the balloon or stent of the FW catheter may be advanced, retracted or rotated against the treatment vessel wall during manipulation of the distal end of the guide wire to the treatment site, increasing the likelihood of vessel trauma. No such concern exists when using OTW or RX catheters as the guide wire can first be negotiated into position prior to advancing the catheter itself.Another difficulty with FW catheters is encountered if a dissection occurs within the vessel during inflation of a balloon. A dissection of the vessel typically involves some perforation or tearing of the vessel wall in proximity of the balloon inflation or other therapeutic intervention. In such instances it may be pertinent to deploy a stent within the dissected segment of vessel and it is critical to ensure the guide wire remains positioned across the damaged section of vessel because it may not be possible to re-cross a guide wire through the dissected segment of vessel to enable advancing a stent delivery catheter to the dissected segment of vessel. If a dissection occurs when using a FW catheter, with a non-removable guide wire, it will not be possible to leave the guide wire in position and remove the FW catheter prior to stenting as the guide wire is an integral part of the catheter.
It is therefore desirable to have a guide wire system that enables conjoining of a guide wire and an OTW catheter device so that the conjoined devices incorporate the advantages of a FW catheter but not the disadvantages of a FW catheter. It is also desirable for the conjoined devices to incorporate the benefits and advantages of OTW catheters and RX catheters but not the disadvantages. It is also desirable to have a guide wire system that enables coupling of a guide wire and a catheter based device for the treatment of many different medical device procedures in areas such as interventional radiology, interventional bronchoscopy, gastroenterology, urology and other areas of treatment.